Sedimentary Facies Of Dachang Stratum In Southwest Guizhou

Dachang stratum in Southwest Guizhou widely distributed, but in a different mines have different names. In previous studies it is often restricted to a small range of comparison, the lack of systematic study of a larger range. In this paper, by conducting basic geological, geochemical analysis, sedimentary facies analysis, to divide the sedimentary facies for Dachang stratum in Southwest Guizhou. And by fluid inclusion studies and laser Raman spectroscopy, we discussed the evolution of the Qinglong antimony ore ancient reservoir and the role played by Dachang stratum in this evolution. Geochemical analysis showed that the original rock of Dachang stratum should be mainly alkaline basalts and erupted in continental rift environment, mainly volcanic material from the mantle. The main difference between the Dachang stratum and Emeishan basalt in the chemical elements is that,K2O content of Dachang stratum is several times or even hundred times to the content of Na20, and K2O content of Emeishan basalt is generally less than Na20 content. By carrying out field geological work, identification sheet and results of previous studies, Dachang stratum in study area is divided to explosion facies, fluvial facies, estuary facies and shoreland facies. Explosion facies have the largest distribution in all sedimentary facies, further divided into airfall deposit subfacies and airfall under water deposit microfacies. Fluvial facies and estuary facies only distributed in the vicinity of Qinglong Dachang area. Shoreland facies are distributed near the line of Qincaiping through Louxia to Fangmaping. By studying the fluid inclusions, that ingredient of organic inclusions in Qinglong antimony ore ancient reservoirs is similar with ingredient of organic inclusions in Qinglong antimony ore. Ancient reservoirs located in the northwest wing of Dachang anticline. Qinglong antimony ore located in the core of Dachang anticline. Ancient reservoirs and Qinglong antimony ore were very close, and have a similar degree of evolution and possible kinship. Dachang stratum and the unconformity between Dachang stratum and Maokou limestones may be the major migration pathways for fluid between ancient reservoirs and antimony ore. Dachang stratum may be an important channel for fluid migration between the different geological in Southwest Guizhou.